Hello,   We are implementing a network for AV applications, like Dante audio over IP, NDI and lighting control.   Last year, we implemented the core part and 3 access switches and this year we added quite a bunch of access switches.   Before this year's extension, we had IGMP snooping enabled on the whole network and things worked fine - all multicast traffic was flowing as expected.   The following multicast groups are used for all devices to work properly: Group address Port Usage 239.255.0.0/16 4321 ATP Multicast Audio 239.69.0.0/16 5004 AES67 Multicast Audio (RTP / AVP port) 223.0.0.233  8700-8706 Dante Control  224.0.1.129-132 319, 320 PTP 224.0.0.251 5353 mDNS 224.0.0.230 – 233 8700 – 8708 Multicast Control and Monitoring 239.16x.x.x   ACN Yamaha 239.192.x.x-239.195.x.x SDT session, dyn. Based on IP and MAC Shure 239.254.1.1 9998 Logging 239.254.3.3 9998 PTP Logging (if enabled) 239.254.44.44 9998 Logging 239.255.254.253  8427 Multicast SLP Shure/Yamaha 239.255.255.250  1900 SSDP, service discovery Shure 239.255.255.253   SLP multicast address Shure 239.255.255.255 9875 SAP (AES67 discovery)   After adding the access switches this year, we have a problems with multicast traffic reaching them from other switches. Only on the NEW switches. They are all connected over a trunk LAGG to the core switches with the same admin VLAN and allow all VLANs.   So we had to limit IGMP snooping to the core switches to re-gain normal functionality. This is a problem for access points and 100Mbps devices, we can't leave the network in this situation.   Does someone know what can be a problem for multicast traffic on Meraki switches? All switches are MS425-32, MS125-24/48. And how on earth this problem happens only on new switches?? Is there a hardware change?   Thanks, Daniel             ... View more